Răspuns:
6 la orice putere se termina in 6
5 la orice putere se termina in 5
u(7^1 )= 7 ; u(7^2) = 9 ; u(7^3) = 3 ; u(7^4) = 1
200 : 4 = 50 => u(7^200) = u(7^4) = 1
7^200 = > 200 : 7 = 28 rest 4 = > se termina in 1
U(6 + 5 + 1) = U(12) divizibil cu 2
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